I looked to my right, through the connecting door, but couldn't see the source.
On the bridge it was much the same, except they could see the source of the effects.
He saw at a single glance the source of their difficulty.
Everyone stopped what they were doing and ran to see the source of the explosion.
One only has to spend a little time in court to see the overwhelming source of child abuse cases.
The room was lit, though I couldn't see the light source.
Taking a good look in the mirror is a first step, though you may not be able to see the source.
The light was soft, indirect, and he had never seen the source.
We do not always see the source of the conflicts in question.
He could still not see the source of the sound.